textproduct: Quad Cities

KEY MESSAGES

- A clipper-like system late tonight into Tuesday is forecast to bring scattered showers and isolated thunderstorms to the region (20-50%).

- Warm up expected late week with temperatures reaching into the 70s/80s by Friday as the next storm system approaches.

SHORT TERM /THROUGH TONIGHT/

Issued at 215 PM CDT Mon May 11 2026

Beautiful weather expected for the rest of today with light winds and highs in the mid 60s to low 70s for most areas. High pressure will shift to the east tonight into the Great Lakes region, resulting in an increase in southeasterly flow with gusts reaching 20-25 kts late. A shortwave trough axis is forecast to reach central to northern Minnesota by early Tuesday AM with a trailing zone of WAA and associated scattered showers extending southward into portions of north-central Iowa. Given this placement, most of the local area should stay dry overnight with plenty of dry air to overcome before the lower atmosphere begins to saturate more into mid Tuesday morning.

LONG TERM /TUESDAY THROUGH MONDAY/

Issued at 215 PM CDT Mon May 11 2026

Tuesday...A shortwave trough diving south from Ontario will generate a mid-level f-gen band over Wisconsin and northern Illinois, providing cloud cover and light rain to our northern CWA. As the clipper-like low pressure swings into northern Wisconsin, a cold front is pushed southward into the area. Limited moisture return from the south should limit precipitation coverage to along the front. Storms that do develop are forecast to move southeastward around 45 mph. Therefore, it will not take a lot of mixing to transport this momentum to the surface which is why the SPC has a Marginal (1 out of 5) Risk for severe storms across the eastern outlook area with damaging winds as the primary threat. Regardless of storm development, southwesterly winds are forecast to gust up to 35-45 mph ahead of the front and advect in warmer air as seen with highs forecast in the upper 70s to lower 80s. Areal coverage of storms for the late afternoon and evening looks to remain isolated with limiting factors being meager low-level moisture (dewpoints in the 40s to lower 50s) and weak instability (HREF MUCAPE only a few hundred J/kg up to ~500 J/kg).

As the cold front clears the area by sunset, northwesterly flow settles in with gusts still up to 35 mph possible. As the skies clear out, the lows should drop back into the low 50s despite the huge warm up during the day.

Wednesday...Northwesterly flow aloft returns as the region will be sandwiched between a longwave trough to the east and ridging over the Rockies. Conditions will be mostly dry besides some light lingering showers in northern Illinois from a weak surface trough on the backside of the low pressure over Upstate New York. Northerly flow is forecast to cool down highs Wednesday back into the mid-60s to mid-70s across the area, similar to conditions on Monday. Lows on Wednesday night are forecast to drop back into the 40s as the winds go nearly calm. There is the potential for radiational fog to develop, but the probabilities are still low.

Thursday-Friday...A shortwave trough over the northern Rockies ejects into the Northern Plains, shifting the ridge axis over the Upper Mississippi River Valley on Thursday. This will deepen a developing mid-latitude cyclone over Saskatchewan as a cold front propagates east of the Rockies. Once again, the low-level flow returns to southerly ahead of this next low pressure system, advecting in warmer and more moist air, but unlike Tuesday, the prolonged period of return flow will allow PWATs to gradually climb Thursday into Friday morning above 1 inch. A pre-frontal trough will support isolated showers and thunderstorms overnight on Thursday into Friday morning, but model uncertainty grows as we get into Friday on the exact timing of the cold front. The ECMWF ensembles have the low pressure over Saskatchewan booking it eastward across Canada with the mid-level trough, pushing the front through on Friday night, but the GFS ensembles has a bimodal distribution in solutions with a group agreeing with the ECMWF and another with a slower low pressure system over the Northern Plains. This will have a great influence on the timing and coverage of storms that develop on Friday as seen by the spread in LREF 6-hourly precipitation of 0.25 inch across the CWA.

Regardless, there will be a warming trend starting Thursday into Friday with highs in the 80s becoming more likely (40-60%) across the entire CWA.

Saturday-Sunday...While Saturday's weather will be dependent on if the cold front Friday night clears the area, there is greater agreement among ensemble models that another low pressure system will develop across the Great Plains on Sunday, bringing PoPs back up across the region. PWATS will likely stay above 1 inch through the weekend as seen in the LREF probability of exceedance being 60-80%, keeping the threat of heavy rainfall elevated.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 647 PM CDT Mon May 11 2026

VFR conditions will continue throughout the TAF period. An area of high pressure will continue to slide eastward tonight with strengthening southeasterly winds expected overnight tonight. An intensifying southwesterly 35 to 45 knot low-level jet will develop as well, leading to a period of low-level wind shear tonight into early Tuesday morning. A cold front will then sweep through the area Tuesday that will bring chances of showers and isolated storms (20-50%), but plenty of dry air near the surface should maintain VFR conditions. We will continue to use PROB30 groups for the rain chances. After sunrise, there will be a period of gusty winds to around 30 knots expected Tuesday.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.